Error: XYZ has no ancestry information.

This was using the Eclipse SVN client. I tried and tried and couldn't get around this error. Eventually I gave up and just moved my workspace to a new location, and checked out all my projects again.

There doesn't seem to be ANY help on the SVN mailing list about this.

Error: commit item XYZ has copy flag but an invalid revision

I think I managed to achieve this after moving a folder in Eclipse (which resulted in a svn add and svn delete), renaming the folder back to the deleted folder manually in Explorer, and trying to commit. No series of updates or cleanups would resolve this.

The solution is to delete not only the containing folder of the folder, but the containing folder of that folder as well. You can then update and re-merge your changes as necessary.

"So someone smarter than I continued where I left off and discovered that I was mostly right, there was a memory leak. But when I had tumbled off to get sleep, exhausted, he soldiered on, and tracked that leak to the DAV module (moddavsvn) in Apache. The problem, apparently, is that the DAV module was performing the authentication steps for every directory, every time it was accessed, and the leak was leaking during the auth process. Thus, in a large tree, the dozens or hundreds of auth steps would end up leaking the module into instability. The solution was to tell the DAV module not to reauthenticate for every path underneath the main one once the user had been authenticated into the repository. To do this, add the following statement to the apache config (in the vhost entry for the repo, in our case):

One possible symptom of this problem is that you can svn update individual directories fine, but trying to svn update a huge directory fails. Another solution may be to refactor your repository into smaller chunks, to prevent this memory/time/stability leak.

Alternately

You might have a file listed locally as added, but remotely not within the repository. Check your Apacheerror.log for messages like these:

I was getting this wildly unhelpful error only in certain circumstances: SVN was working fine to update, commit and checkout, but it was failing when trying to merge branches. In particular, my SVN was setup to host via Apache using mod_dav_svn and using Digest authentication rather than SSL.

One step to try and work out these problems is by only issuing one command at a time:

Another thing you can try to do is to set neon-debug-mask in your client servers configuration file, to get much more detailed information on the authentication process (refer here to understand the value of this field):

neon-debug-mask = 138

You might also have a problem with svn-auth.htdigest file having correct group permissions, but not correct user permissions.

$ sudo chown www-data svn-auth.htdigest

I don't know what the actual cause of the problem was, but as I was behind a web proxy, using a different proxy (or removing the proxy entirely) solved the problem.